Conventionally, a water-lubricated resin bearing has been used in a hydraulic machine such as a Kaplan turbine. In general, a phenol resin which is a thermosetting resin is used as this resin, but since the phenol resin does not have high wear resistance against hard foreign matters such as soil and sand in water, clean water from which foreign matters are removed via a strainer is supplied as a lubricant to a sliding surface of the bearing. Further, since water absorption of the phenol resin is high, when the bore of the bearing is machined, the phenol resin is retained in a state of being dipped in water in advance, and machining is performed after the phenol resin is sufficiently swelled. This is because the phenol resin swells in operation and the bearing gap becomes small, which impairs bearing performance. Further, an adhesive is used for joining a base metal and a bearing material, a cylindrical bearing is formed so as to suppress increase in local contact pressure and transmit a bearing load to the entire base metal, and a bearing length is long for increasing a bearing load capacity itself. In this case, if shaft vibrations are large, an uneven contact may occur between the shaft and a bearing end portion, causing a failure, abnormal wear, or the like.
On the other hand, there is known a device in which the bearing material is ceramic and the bearing structure is a pad type. This pad-type ceramic bearing device is characterized in that it has a pad-type bearing disposed around a rotary shaft and having a ceramic layer on a sliding surface and a load supporting member supporting this pad-type bearing, river water is used as a lubricant for the bearing, and foreign matter entrance preventing means are provided on or around the pad-type bearing for preventing entrance of foreign matters between the pad-type bearing and the bearing load supporting member. The foreign matter entrance preventing means are constituted of a leaf spring, a coil spring, a pressure adjusting mechanism for adjusting a contact pressure of the pad-type bearing via an adjuster having a spherical tip shape, and an elastic supporting mechanism elastically supporting the pad bearing from a lower side with two or more coil springs, and by operation of these mechanisms the pad bearing is in slide contact with an opponent rotary shaft via a water film.
Moreover, there is known a pad-type bearing in which a bearing slide contact surface material is a resin and polyphenylene sulfide series or fluorine-based resin is used for this resin. It is inferior in wear resistance but is superior in shock resistance compared to ceramic materials, and thus allows to effectively utilize an elastic press-contact mechanism which elastically presses the bearing slide contact surface against an opponent shaft sleeve. Consequently, entrance of foreign matters can be prevented by press-contact of the shaft and the bearing during a stoppage period, and increase of the bearing gap can be prevented when the resin wore off, enabling formation of an appropriate water film.
Further, there is known a guide bearing device in which a bearing slide contact surface material is a polyetheretherketone resin, and a guide sector is press contacted by a spring or press contacted by a damper and a spring. Reliability of the guide bearing can be improved by absorbing and damping axial displacements accompanying axial vibrations by the spring. When water is used as a lubricant, as compared to the case where turbine oil is used, rigidity of a wedge film and a damping constant decrease to about one several tenths. However, the guide sector is pressed against a rotary shaft by an adjusting bolt (or a spring or a spring and a damper) provided on a rear surface thereof, and the gap between the rotary shaft and the guide sector is small. Thus, excessive vibrations of a rotor do not occur, and a rotary electrical machine can be operated normally.
Further, there is known a guide bearing device for rotary electrical machine in which a pivot pivotally supports a guide bearing from an outside in a radial direction, the guide bearing is supported in a vertical direction by a support plate, and a bearing gap can be adjusted by performing expansion and contraction of the pivot by an actuator connected to the pivot in the guide bearing device for rotary electrical machine. This device rationalizes adjustment of the bearing gap that requires skill in the guide bearing device in which the rear surface of the guide bearing is supported with the pivot, and a vertical direction of the guide bearing is supported with a flat surface. When dispersion of this bearing gap is large among guide bearings, this adversely affects bearing performance such as bearing load capacity, bearing temperature, and the like.
Furthermore, there is known a bearing gap adjusting device for guide bearing device for vertical shaft rotary electrical machine in which a pad supporting part such as an adjusting bolt is not a pivot, but a spherical pivot fitted in a pad recessed portion is provided for adjusting the bearing gap.
Further, regarding positioning of a thrust bearing, there is known a thrust bearing in which the outer wheel of a ball bearing, which is a spherical bearing, is fixed to or closely contacted with a pad lower side portion, and the inner wheel of this ball bearing is attached to a pad holder, thereby allowing adjusting a radial tilt and a circumferential tilt with reference to a pivot. In the case of such a structure, the thrust bearing can tilt by a required amount about the pivot, and thus an oil film pressure with respect to a thrust load can be generated constantly between the pad and a thrust collar.